In the conventional protocol such as an Open Shortest Path First (OSPF), each node (e.g., router) within a domain recalculates the routing information (route recalculation) and then switches over to the new route for transfer, upon occurrence of a failure.
FIG. 11 is an explanatory view of the conventional art.
For example, in the case of using the existent protocol such as the OSPF, a Designated Router (DR) that is a node for managing a Link State Database (LSDB) is provided. In an example of FIG. 11, the node N-1 is DR.
For example, when a failure occurs at the node N-3, the adjacent nodes like N-1 detect the failure. The node N-1 that detects the failure updates the LSDB (database for managing the link state). The node N-1 sends a Link-State Advertisement (LSA), and notifies the information of updated link state to each node. At all the nodes N-1, N-2, N-4 and N-5, the route recalculation is performed.
In patent document 1, there were disclosed a network connection apparatus and a network connection method in which as a countermeasure against failure at the single node, each node generates and holds the information regarding the route switching (interface change for inter-node link) when the failure occurs as a scenario, and makes recalculation for updating a routing table with an existent function such as the OSPF.
Also, in patent document 2, there were disclosed a network management apparatus that, after receiving a failure, changes the network configuration, and notifies it to each relevant network apparatus, and a network apparatus that, after receiving the new network configuration, recalculates the routing table.
Further, in patent document 3, there was disclosed a path control protocol processing method with a Global Megamedia Network-Connectionless (GMN-CL) is separated into a path control process and a transfer control process to manage a path control protocol of the same kind as the same user group.